Diaphragm for sound-reproducers.



B. FRITZSCH.

DIAPHRAGM FOR SOUND REPRODUCERS.

APPLICATION FILED MAY 15, 1916.

1,217,294. Patented Feb. 27,1191?.

SH01/new BERNHARD FRITZSCH, 0F CNCINNATI, OHIO..-

DIALPHRAGM FOR SOUND-REPRODUCERS.

Specification of Letters Patent.

Application filed May 15, 1916. Serial No. 97,492.

To all 'whom it may concern.'

Be it known that I, BERNHARD FRrrzsoH, a citizen of the United States,and residing at Cincinnati, in the county of Hamilton and State of Ohio,have invented a new and useful Improvement in Diaphragms forSound-Reproducers, of which4 the following specification is a fulldisclosure.

My invention relates to improvements in a phonograph sound box.

The object of the invention is to-improve the tone quality and tosimplify the mechanism, the particular improvement being in -regard tothe structure and characteristic of the diaphragm and the needle arm.

The features of the invention will be more fully set forth in thedescription of the accompanying drawings, forming a part of thisspecification, in which Figure 1 is a side elevation of the sound box.Fig. 2 is a rear elevation. Fig. 3 is a top plan view. Fig. i is asection on line Y `4--4, Fig. 1. Fig. 5 is a plan view ofthe diaphragm.Fig. 6 is a side elevation thereof. Fig. 7 is a plan view of the needlearm.l Fig. 8 is a side elevation thereof. Fig. 9 is a top plan view ofthe sound converging arm.

The sound box comprises the annular -members 1 and 2, screw-threadedtogether,

being `interiorly recessed for engaging the periphery of diaphragm 3,the diaphragm preferably being held between the rings 4, which rings areclamped in position between the inner recessed peripheral surfaces ofthe annular members 1 and 2.

The diaphragm is a thin wooden disk preferably of'maple, the centralportion of the inner surface being formed preferably integrally with theconical boss 7 having its base adjacent or joining with the disk. Thedisk is mounted in its holder with its boss projecting side inward sothat the boss will extend toward or centrally into the conduit of thesound arm or amplifier. The opposite or outer side of the disk has tworibs 8 fixed thereto and located to run or extend counter to the rainand approximately at opposite sides o the axis or center of the disk.These ribs sustain the shape of the disk and also modify the diskvibrations.

l The diaphragm and the portion of holding member. 1 are spaced apart toconstitute the sound generating chamber 20, there being a centralorifice 21 through the medial Patented Feb. 27 1917.

portion of member 1 leading from'the sound chamber to the sound arm 22.The conical boss 7 is secured centrally to the inner face of the woodendiaphragm with the cone concentrically projecting into the opening 2l soas to constrict but not close the passageway between the soundgenerating chamber and sound arm. Apparently this cone acts as agovernor in this sound generating chamber to prevent overvibration, theeffect being to prevent blasting or sounds produced by improperdiaphragm operations: A thin lwooden diaphragm made say or violinmaterial is more resilient and resonant than mica or materialsheretofore used on commercial machines and I have obtained betterresults with such a wood diaphragm by rigidly securing the needle arm toa resilient fulcrum, such as a leaf spring, in the plane of the disk,instead of employing the pivotal type of fulcrum. There seems to becoaction or the relationship of action and reaction between the woodendisk with the weighted center and this resilient fulcrum. As one end ofthe needle arm is rigidly secured to this leaf spring andthe other endof the needle arm is rigidly secured yto the center of the wooden diskoppositethe cone weight, a remarkably increased sound volume is producedwhen the wooden disk with its central, conical boss is used with theresilient needle arm .fulcrum.

On the outer'periphery of the member 2 are projected two clamping posts9, between which is secured a fiat or leaf spring needle arm support 10being held in place by screws 11. The needle arm support 12 has an innerend 13 connected to the exact center of the outer .surface of thediaphragm opposite the central portion o f the conical boss. The outerend of the arm is formed with the oset portion 14 extending over theperipheral edge of the annular member 2, and formed with a needle socket15 for the needle 16, said offset portion having a sloty adjacent theperiphery of the annular member 2 into which fits the middle portion ofthe spring 10, the spring and arm being .rigidly secured together, as bysoldering.

position is employed, provision must be made 1 to prevent overvibration. This ll accomplish by the conical boss 7, which not onlysoundbox is robbed of all the shrillness, and

hasparticular, adaptation to recording and reproducing overtones.v Thisis particularly 'noticeable in piano records, generally the mostdifficult for reproductions, and' with my sound-box, thesingingtone ofthe piano is faithfully reproduced, and at Jthe same s .time the volume'of the sound is materially increased.

Having described my invention, ll claim 2,--f

1.`A diaphragm for a sound reproducing and recordingy device comprisinga thin wooden disk having a centrally projecting conical boss upon oneside With the hase of the cone joining with the disk.

2. A diaphragm for a sound reproducing and recording device comprising adisk having a conical boss axially projecting from `Vone side With thebase of the boss joining with said disk.,

3. A sound reproducing and recording devicen comprising adiaphragmholder, .having a central sound passage, adiaphragm marginallysecured Within said'holder, the inner side,of the disk and holderforming ya sound chamber communicating With said holder soundpassage,"`said diaphragm having a conical boss projecting centrally fromits inner face to 'extend axially toward or into said sound passageand'with the base of the cone joining With' thev disk.

lln Witness whereof, l hereunto subscribe my.- name, as attested by thetWo subscribing Witnesses. l

` BERNHARD FRITZSCH. Witnesses: Y

CLARENCEB. FOSTER, L. A.y BUCK.

